/Engine/Source/Runtime/GeometryCore/Public/Util/BufferUtil.h
Count number of elements in array (or within requested range) that pass Predicate test
number of values in array that returned true for Predicate
namespace BufferUtil { template<typename T> int BufferUtil::CountValid ( const [TArray](API\Runtime\Core\Containers\TArray)< T > & Data, const [TFunction](API\Runtime\Core\GenericPlatform\TFunction)< bool(T)> & Predicate, int MaxIndex, int StartIndex ) }